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Oldman1950
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Help with Hepburn Chamber
Aug 21st, 2026 at 12:39pm
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I have a Hepburn Short Range Creedmoor marked 38-1 3/4" that I need some help with. It seems as the chamber on this rifle is much tighter than the standard chamber for the 1 3/4" Hepburn. I am trying to use 303 British brass trimmed to 1 3/4" and run thru a CH sizing die. The brass only enters the chamber about half of the way. I have done a chamber cast (Picture attached). The lead on this chamber is long as noted in the picture but too short to be a 38-50 chamber. According to Tom Rowe's book on Hepburn's that there was a cartridge called the 38-45 Remington Special. Would anyone happen to Have one of these rounds and be so kind to take a measurement of it for me? I need the head dia. just ahead of the rim. I am waiting on a small boring bar and will try and make a sizing die. Wish Me LUCK.
Thank You,
A. J. Palik   
  
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joelpend
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Re: Help with Hepburn Chamber
Reply #1 - Aug 21st, 2026 at 1:20pm
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Looks close to a 375 Winchester.
  
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Oldman1950
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Re: Help with Hepburn Chamber
Reply #2 - Aug 21st, 2026 at 2:36pm
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joelpend
I think you might be heading me in the right direction. I would still have to make a sizing die but much less sizing than with the 303 British.
A. J. Palik
  
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Dellet
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Re: Help with Hepburn Chamber
Reply #3 - Aug 21st, 2026 at 3:37pm
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If you’re just trying to form brass, a 38-55 cut down or 30-30 necked up and cut down would be a whole lot easier
  
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Oldman1950
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Re: Help with Hepburn Chamber
Reply #4 - Aug 21st, 2026 at 4:24pm
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A 30-30 Winchester will fit the chamber but I am worried that having to be blown out that far would weaken it. If it was that simple I have plenty 0f 30-30 brass. I am guessing that the 375 brass might be a little more substantial. I only want to make this brass once. 
A. J. Palik
  
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Dellet
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Re: Help with Hepburn Chamber
Reply #5 - Aug 21st, 2026 at 4:48pm
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For me it just seem easier to get a mandrel and expand the necks of a 30-30 or just trim a 38-55, than it is to trim the base of a 303. 

If you need the added safety of 375 Winchester brass, you’re probably pushing that poor old Hepburn a little too hard anyway.
  
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Bulseyetom
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Re: Help with Hepburn Chamber
Reply #6 - Aug 21st, 2026 at 5:56pm
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I wonder if somebody was trying to recreate the 38-50 Maynard with a 38-55 reamer run in short?  I don't think it would be a problem to shorten some 30-30 brass and fireform it to see how it works.  If you use patched bullets you would not need a sizer.  The 30-30 shortened would possibly be better than 375 shortened as I think that the brass for the 375 is thicker and might need to be neck turned.  Tom
  
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Oldman1950
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Re: Help with Hepburn Chamber
Reply #7 - Aug 21st, 2026 at 6:49pm
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I will in NO WAY hotrod the Hepburn. I will be breach seating with a bullet weight between 250-300 grains. Hope to be able to run it no faster than 1400fps. My shooting will be off the bench and this OLD body (75yrs) can't take much more recoil than that.
My usually shooting is with a 32-40 win. and a 200 grain bullet at 1400fps. Over the last 10 years or so I have at least 100 shots on each piece of brass and out of the 100 cases I started with I still have 97. One got stepped on and the primer pockets started to get loose on the other two. I have a lathe and the time it takes to make some brass that will hold up with time. I actually enjoy getting an old gun up and running again.

P.S. Don't tell anyone but I am enjoying this discussion

A. J. Palik
  
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joelpend
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Re: Help with Hepburn Chamber
Reply #8 - Aug 21st, 2026 at 7:11pm
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If you can anneal the 30-30 brass it may expand just fine.
  
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Bulseyetom
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Re: Help with Hepburn Chamber
Reply #9 - Aug 22nd, 2026 at 12:00am
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It looks to me like a 375 winchester case shortened to 1.800" would still be 0.400 at the neck.  Since you will be breech seating you don't need to worry about the neck thickness.  Brass is readily available now and I would buy some and try a factory length case to see if it chambers then shorten as necessary so that it chambers.  With the long leade you might be able to use brass longer than 1 3/4".  I don't see the need for any dies at all.  Good luck.  Tom
  
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jhm
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Re: Help with Hepburn Chamber
Reply #10 - Aug 22nd, 2026 at 7:09pm
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My latest Hepburn was a 40-70 that uses .405 Hornady brass. They wouldn't chamber at first as the neck area was a bit thick. I made a mandrel to hold them and turned about .003 off the neck on my lathe so the case wall was a uniform .010 thick. Now they chamber without binding. You may not have a lathe but maybe know someone who does to turn the bases for you. I think there would be ample thickness in the base. Just a thought...



JMH
  
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joelpend
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Re: Help with Hepburn Chamber
Reply #11 - Aug 22nd, 2026 at 7:37pm
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The SAAMI for 38-55 is a couple thou smaller than 375 Win in front of the rim.
  
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Oldman1950
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Re: Help with Hepburn Chamber
Reply #12 - Aug 25th, 2026 at 5:38pm
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Problem solved.
In todays mail I received 100 Starline 375 Win brass. I shortened it to 1.800 and had to turn about 6 thousands off of the Base of the cartridge and about 10 thousands off of the rim dia. The brass now enters the chamber, and the block closes without problems. I have 30 pieces of brass done and will finish the other 70 and then fire form them with 10 gr. of Unique and the remainder of the case full of cream of wheat. It takes some time doing all of this, I have the lathe and the tooling but the end results will be worth the work.
A. J. Palik 
  
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